Torque converter coupling

ABSTRACT

A driving coupling for the torque transmission in the transmission line of a motor vehicle includes a shaft-hub coupling provided with longitudinal toothings for the releasable coupling of a crankshaft with a coaxially arranged hydrodynamic torque converter. The longitudinal toothings of the shaft-hub coupling have tooth cross-sections which become larger and smaller respectively in the longitudinal direction of the teeth. An elastomer layer is situated at least between the tooth flanks of the shaft and the hub which transmit the torque.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a torque converter coupling to a crankshaft inthe transmission line of a motor vehicle and a method of coupling atorque converter to a crankshaft.

It is known to provide, in the transmission line of a motor vehicle, adriving coupling for the torque transmission by means of a shaft-hubcoupling provided with longitudinal toothings, for a releasable couplingof a crankshaft with a hydrodynamic torque converter arranged in acoaxial manner. The longitudinal toothings of the shaft-hub couplinghave tooth cross-sections which become larger and smaller respectivelyin the longitudinal direction of the teeth.

German Patent Document DE 197 47 962 A1 describes such a drivingcoupling for torque transmission. It was found that, because of therequirement of the self-locking of the driving coupling againstreleasing forces during torque transmission, the tooth flanks of thetooth cross-sections which become larger and smaller respectively mustbe made in a very precise manner, resulting in high manufacturing costs.In addition, as a result of misalignments between the torque converterand the crankshaft result in a poor contact pattern of the tooth flanks,which is always disadvantageous during torque transmission.

It is therefore an object of the invention to provide a releasablecoupling between a torque converter and a crankshaft which can beestablished easily and compensates misalignments with zero backlash.

According to the invention, a driving coupling is provided in thetransmission line of a motor vehicle for torque transmission by means ofa shaft-hub coupling. The shaft-hub coupling has longitudinal toothingsfor a releasable coupling of a crankshaft with a hydrodynamic torqueconverter arranged in a coaxial manner. The longitudinal toothings ofthe shaft-hub coupling have tooth cross-sections which become larger andsmaller respectively in the longitudinal direction of the teeth. Thedriving coupling has an elastomer layer situated at least between thetooth flanks of the shaft and the hub.

Such a longitudinal toothing with an elastomer layer between the shaftand the hub has the advantage that zero backlash is created in the caseof an axial prestressing even when misalignments occur between thecrankshaft and the torque converter. In addition, in the case of acoupling between a crankshaft and a hydrodynamic torque converterarranged coaxially, a good contact pattern is achieved by means of sucha shaft-hub coupling, even in the case of an external centering.

In a preferred embodiment of the invention, the elastomer layer isapplied to the shaft toothing and/or to the hub toothing. This has theadvantage that the shaft-hub coupling can be produced in a simplemanner, particularly if the elastomer layer is vulcanized onto thetoothing.

An advantageously cost-effective variant of the driving coupling ischaracterized in that the longitudinal toothings of the shaft-hubcoupling are shaped of sheet metal.

If the tooth cross-sections, which become larger and smallerrespectively in the longitudinal direction of the teeth, are achieved byway of such a change of the tooth width of the longitudinal toothings ofthe shaft-hub coupling, a relatively large change of the toothcross-section is possible as a result of the high coefficient offriction between the elastomer and the steel. This results in zerobacklash even in the case of small axial tolerances. Preferably, a wedgeangle of the widening or narrowing teeth from 8 to 15 degrees may beprovided.

In another advantageous embodiment of the invention, an axial force isused for the axial fixing of the shaft-hub coupling, which axial forceis generated by an internal converter pressure during the operation ofthe converter.

Such a construction has the advantage that no additional measures haveto be taken for axially securing the shaft-hub coupling. The axial forcein the direction of the crankshaft generated on the basis of the torqueconverter operation presses the conical longitudinal toothings into oneanother without backlash as a result of the elastomer layer.

In addition, for the axial fixing of the shaft-hub coupling, the shaftand the hub can also be form-lockingly connected with one another in aform locking manner. This ensures the coupling between the crankshaftand the torque converter even when the torque converter is not inoperation and therefore no internal converter pressure is present. Sucha form-locking coupling of the shaft and the hub is achieved by knownmachine elements, such as a tension spring mounted in a circumferentialgroove of the hub, or screws screwed in the radial direction into thehub and projecting through the latter.

A preferred embodiment of the invention is described in the followingdescription with the pertaining drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial sectional view of the coupling of a crankshaft to atorque converter according to the invention; and

FIG. 2 is a cross-sectional view of the coupling of the crankshaft tothe torque converter of FIG. 1 in the area of the toothing.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of an end section of a crankshaft 1 having a carriermetal sheet 18 for a starter gear ring 19, which carrier metal sheet 18is fastened by screws 15. In a certain diameter range, the carrier metalsheet 18 is constructed as a longitudinally toothed hub which forms areleasable driving coupling with a driving flange 2 of a hydrodynamictorque converter constructed as a longitudinally toothed shaft. The huband the shaft mesh with one another in a form-locking manner.

By means of a weld seam 3, the driving flange 2 is fixedly connectedwith a housing 4 of the torque converter. The driving flange 2 and thecarrier metal sheet 18 are made of sheet metal. Their longitudinaltoothings have tooth cross-sections which become larger and smallerrespectively in the longitudinal direction of the teeth 6, 7 (FIG. 2).An elastomer layer 5, which is vulcanized either to the carrier metalsheet 18 or to the driving flange 2, is situated between the teeth 6, 7.

The housing 4 is axially displaceable with respect to the crankshaft 1.As a result, the internal converter pressure occurring during theoperation of the torque converter displaces the housing 4 with thedriving flange 2 in the direction of the crankshaft 1, specificallyuntil the shaft hub coupling has zero backlash because of the toothcross-sections on the shaft and the hub and because of the elastomerlayer 5. This means that the driving flange 2 is supported by thecrankshaft 1 in the axial direction by way of the longitudinal toothing.

FIG. 2 is a cross-sectional view of the longitudinal toothings of thecarrier metal sheet 18 as the hub and of the driving flange 2 as theshaft. They are shaped of metal and, as a result of the pushing into oneanother of the crankshaft 1 and the driving flange 2, are connected withone another in a form locking manner. The elastomer layer 5 is situatedbetween the teeth 6, 7 of the toothing of the carrier metal sheet 18 andthat of the driving flange 2. When the crankshaft 1 rotates in thedirection marked by the arrow 11 and torque is transmitted from thecarrier metal sheet 18 to the driving flange 2, the force transmissiontakes place by way of the tooth flanks 12 of the teeth 7 and theelastomer layer 5 to the tooth flanks 13 of the teeth. As a result ofthe tooth cross-sections because of the elastomer layer 5, and becauseof the internal converter pressure, which axially loads the drivingflange 2 in the direction of the crankshaft 1, zero backlash occurs atthe force-transmitting tooth flanks 12, 13 of the releasable drivingcoupling. Even in the event of sudden increases of load or loadfluctuations, the axial force from the internal converter pressureensures that a separation of the tooth flanks 12 of the carrier metalsheet 18 and of the tooth flanks 13 of the driving flange 2 isprevented.

In another embodiment, which is not shown, it is also conceivable thatthe longitudinal toothing is replaced by wedge-shaped claws of radialserrations, which claws project into one another. The wedge angle of theclaws should then be approximately within the range of the self-lockinglimit. The elastomer layer will then correspondingly be applied betweenthe claws.

What is claimed is:
 1. Driving coupling for torque transmission in thetransmission line of a motor vehicle by means of a shaft-hub couplingprovided with longitudinal toothings for a releasable coupling of acrankshaft with a hydrodynamic torque converter arranged in a coaxialmanner, the longitudinal toothings of the shaft-hub coupling havingtooth cross-sections which become larger and smaller respectively in thelongitudinal direction of the teeth wherein an elastomer layer issituated at least between the tooth flanks of the shaft and the hub. 2.Driving coupling according to claim 1, wherein the elastomer layer isapplied to at least one of the shaft toothing and the hub toothing. 3.Driving coupling according to claim 1, wherein the elastomer layer isvulcanized on the at least one of shaft toothing and hub toothing. 4.Driving coupling according to claim 1, wherein the longitudinaltoothings of the shaft-hub coupling are shaped of sheet metal. 5.Driving coupling according to claim 1, wherein the tooth cross-sectionsare achieved by means of such a change of the tooth width of thelongitudinal toothings of the shaft-hub coupling which, during thetorque transmission, is self-locking with respect to a releasing force.6. Driving coupling according to claim 1, wherein, for the axial fixingof the shaft-hub coupling, an axial force is used which is generated byan internal converter pressure during the operation of the torqueconverter.
 7. Driving coupling according to claim 2, wherein the toothcross-sections are achieved by means of such a change of the tooth widthof the longitudinal toothings of the shaft-hub coupling which, duringthe torque transmission, is self-locking with respect to a releasingforce.
 8. Driving coupling according to claim 3, wherein the toothcross-sections are achieved by means of such a change of the tooth widthof the longitudinal toothings of the shaft-hub coupling which, duringthe torque transmission, is self-locking with respect to a releasingforce.
 9. Driving coupling according to claim 2, wherein, for the axialfixing of the shaft-hub coupling, an axial force is used which isgenerated by an internal converter pressure during the operation of thetorque converter.
 10. Driving coupling according to claim 3, wherein,for the axial fixing of the shaft-hub coupling, an axial force is usedwhich is generated by an internal converter pressure during theoperation of the torque converter.
 11. Driving coupling according toclaim 5, wherein, for the axial fixing of the shaft-hub coupling, anaxial force is used which is generated by an internal converter pressureduring the operation of the torque converter.
 12. A driving coupling forcoupling a torque converter to a crankshaft, the driving couplingcomprising: a shaft coupling having longitudinal teeth, the shaftcoupling being connected to one of the torque converter and thecrankshaft; a hub coupling having longitudinal teeth, the hub couplingbeing connected to the other of the torque converter and the crankshaft,wherein the longitudinal teeth of the shaft coupling are engageable withthe longitudinal teeth of the hub coupling; and an elastomer layerpositioned between tooth flanks of the shaft coupling and tooth flanksof the hub coupling.
 13. A driving coupling according to claim 12,wherein the elastomer layer is applied to at least one of thelongitudinal teeth of the shaft coupling and the longitudinal teeth ofthe hub coupling.
 14. A driving coupling according to claim 13, whereinthe elastomer layer is vulcanized on the at least one of thelongitudinal teeth of the shaft coupling and the longitudinal teeth ofthe hub coupling.
 15. A driving coupling according to claim 13, whereinthe longitudinal teeth of the shaft and hub couplings are shaped ofsheet metal.
 16. A driving coupling according to claim 13, wherein thelongitudinal teeth of the shaft and hub couplings are configured in amanner so that they are engaged in a self-locking manner when they areengaged.
 17. A driving coupling according to claim 16, wherein inoperation an axial force, generated by an internal converter pressure,is used to engage the shaft and hub couplings.
 18. A driving couplingaccording to claim 12, wherein the longitudinal teeth of the shaft andhub couplings are configured in a manner so that they are engaged in aself-locking manner when they are engaged.
 19. A driving couplingaccording to claim 18, wherein in operation an axial force, generated byan internal converter pressure, is used to engage the shaft and hubcouplings.
 20. A driving coupling according to claim 13, wherein inoperation an axial force, generated by an internal converter pressure,is used to engage the shaft and hub couplings.
 21. A driving couplingaccording to claim 12, wherein in operation an axial force, generated byan internal converter pressure, is used to engage the shaft and hubcouplings.
 22. A method of coupling a torque converter to a crankshaft,the method comprising: coupling longitudinal teeth of a shaft couplingconnected to one of the torque converter and the crankshaft tolongitudinal teeth of a hub coupling connected to the other of thetorque converter and the crankshaft, wherein an elastomer layer ispositioned between tooth flanks of the shaft coupling and tooth flanksof the hub coupling.
 23. A method according to claim 22, comprisingapplying the elastomer layer to at least one of the longitudinal teethof the shaft coupling and the longitudinal teeth of the hub coupling.24. A method according to claim 23, comprising vulcanizing the elastomerlayer on the at least one of the longitudinal teeth of the shaftcoupling and the longitudinal teeth of the hub coupling.
 25. A methodaccording to claim 22, comprising shaping the longitudinal teeth of theshaft and hub couplings from sheet metal.
 26. A method according toclaim 22, comprising configuring the longitudinal teeth of the shaft andhub couplings in a manner so that they are engaged in a self-lockingmanner when they are engaged.
 27. A method according to claim 22,comprising, in operation, using an axial force, generated by an internalconverter pressure, to engage the shaft and hub couplings.